Current status of magnetic resonance imaging of the orbit.

MR plays an important role in evaluating pathologic conditions that affect the orbit. MR appears to be superior to ultrasound and computed tomography in evaluation of intraocular tumors and fluid collections. In evaluation of noncalcified intraorbital tumors, MR can provide more information regarding orbital apex involvement and intracranial extension. Inflammatory lesions, particularly orbital pseudotumor, can be differentiated from metastatic disease based on differences in signal intensity providing greater specificity than CT. Specific prognostic information may be obtained regarding potentially treatable cases of Graves' disease. Using MR, vascular lesions of the orbit can be assessed for patency or thrombosis without use of intravenous contrast. Demonstration of secondary extension by para-orbital sinus tumors by MR is often helpful in evaluating involvement of the soft tissue structures of the orbit. Potential applications in evaluation of orbital trauma include characterization of orbital hematomas and orbital blow-out fractures.